Documentation generated from fossil trunk
Create and manipulate scale widgets
scale pathName ?options?
|Name||Database name||Database class|
|Some interactions with the scale cause its value to change by "large" increments; this option specifies the size of the large increments. If specified as 0, the large increments default to 1/10 the range of the scale.|
|Specifies the prefix of a Tcl command to invoke whenever the scale's value is changed via a widget command. The actual command consists of this option followed by a space and a real number indicating the new value of the scale.|
|An integer specifying how many significant digits should be retained when converting the value of the scale to a string. If the number is less than or equal to zero, then the scale picks the smallest value that guarantees that every possible slider position prints as a different string.|
|A real value corresponding to the left or top end of the scale.|
|A string to display as a label for the scale. For vertical scales the label is displayed just to the right of the top end of the scale. For horizontal scales the label is displayed just above the left end of the scale. If the option is specified as an empty string, no label is displayed.|
|Specifies the desired long dimension of the scale in screen units (i.e. any of the forms acceptable to Tk_GetPixels). For vertical scales this is the scale's height; for horizontal scales it is the scale's width.|
|A real value specifying the resolution for the scale. If this value is greater than zero then the scale's value will always be rounded to an even multiple of this value, as will tick marks and the endpoints of the scale. If the value is less than zero then no rounding occurs. Defaults to 1 (i.e., the value will be integral).|
|Specifies a boolean value indicating whether or not the current value of the scale is to be displayed.|
|Specifies the size of the slider, measured in screen units along the slider's long dimension. The value may be specified in any of the forms acceptable to Tk_GetPixels.|
|Specifies the relief to use when drawing the slider, such as raised or sunken.|
|Specifies one of three states for the scale: normal, active, or disabled. If the scale is disabled then the value may not be changed and the scale will not activate. If the scale is active, the slider is displayed using the color specified by the -activebackground option.|
|Must be a real value. Determines the spacing between numerical tick marks displayed below or to the left of the slider. If 0, no tick marks will be displayed.|
|Specifies a real value corresponding to the right or bottom end of the scale. This value may be either less than or greater than the -from option.|
|Specifies the name of a global variable to link to the scale. Whenever the value of the variable changes, the scale will update to reflect this value. Whenever the scale is manipulated interactively, the variable will be modified to reflect the scale's new value.|
|Specifies the desired narrow dimension of the trough in screen units (i.e. any of the forms acceptable to Tk_GetPixels). For vertical scales this is the trough's width; for horizontal scales this is the trough's height.|
The scale command creates a new window (given by the pathName argument) and makes it into a scale widget. Additional options, described above, may be specified on the command line or in the option database to configure aspects of the scale such as its colors, orientation, and relief. The scale command returns its pathName argument. At the time this command is invoked, there must not exist a window named pathName, but pathName's parent must exist.
A scale is a widget that displays a rectangular trough and a small slider. The trough corresponds to a range of real values (determined by the -from, -to, and -resolution options), and the position of the slider selects a particular real value. The slider's position (and hence the scale's value) may be adjusted with the mouse or keyboard as described in the BINDINGS section below. Whenever the scale's value is changed, a Tcl command is invoked (using the -command option) to notify other interested widgets of the change. In addition, the value of the scale can be linked to a Tcl variable (using the -variable option), so that changes in either are reflected in the other.
Three annotations may be displayed in a scale widget: a label appearing at the top right of the widget (top left for horizontal scales), a number displayed just to the left of the slider (just above the slider for horizontal scales), and a collection of numerical tick marks just to the left of the current value (just below the trough for horizontal scales). Each of these three annotations may be enabled or disabled using the configuration options.
The scale command creates a new Tcl command whose name is pathName. This command may be used to invoke various operations on the widget. It has the following general form:
pathName option ?arg arg ...?
Option and the args determine the exact behavior of the command. The following commands are possible for scale widgets:
Tk automatically creates class bindings for scales that give them the following default behavior. Where the behavior is different for vertical and horizontal scales, the horizontal behavior is described in parentheses.
If the scale is disabled using the -state option then none of the above bindings have any effect.
The behavior of scales can be changed by defining new bindings for individual widgets or by redefining the class bindings.